1. Technical Field
The present invention relates to a facsimile, and in particular, to a method and apparatus for receiving a facsimile message from a calling facsimile in a facsimile connected to an external telephone.
2. Related Art
Communication between facsimiles for transmitting a facsimile message is attained by performing a protocol according to a predetermined transmission control procedure. The term "facsimile message" refers to an original document on which picture or text is formed. In the facsimile, the transmission control procedure conforms to a recommendation specified in "Terminal Equipment and Protocols for Telematic Services Recommendations T.30 (Blue Book)", ITU (International Telecommunication Union) CCITT (International Telegraph and Telephone Consultative Committee) Volume VII-Fascicle VII.3. In accordance with the transmission control procedure specified in the recommendation, when setting up a call between a calling facsimile and a called facsimile, the calling facsimile transmits a calling tone (CNG) to the called facsimile. Upon checking such a calling tone received from the calling facsimile, the called facsimile transmits a CED (called station identification) signal to the calling facsimile, thereby to set up the call. The calling tone check is attained when the called facsimile has detected two calling tones. After completion of such a call set up, the actual facsimile message is transmitted between the calling and called facsimiles.
Although a facsimile may have a handset therein, the facsimile may be connected to an external telephone so as to allow a user to make a telephone call or receive an incoming call, even in case of a power failure. The external telephone may include a telephone answering machine (TAD).
However, in a facsimile connected to an external telephone, upon hearing a ring tone transmitted by a calling facsimile so as to transmit a facsimile message, a user of the called facsimile may pick up the handset of the external telephone, thereby connecting the telephone line (i.e., a line-on status). Then, the calling facsimile transmits the calling tone to the called facsimile. Upon hearing the calling tone, the user may leave the handset off, thereby disconnecting the telephone line (i.e., a line-off status) before the called facsimile completely checks the calling tone transmitted from the calling facsimile. Accordingly, the called facsimile cannot receive the facsimile message.
As described above, if the external telephone assumes a line-off status before the called facsimile completely checks the calling tone transmitted from the calling facsimile, the facsimile cannot receive the facsimile message due to disconnection of the telephone line.
The following patents are considered to be representative of the prior art relative to the invention disclosed herein: U.S. Pat. No. 5,703,699 to Kim entitled a Method for Automatically Receiving Image Data in Facsimile System Regardless of Whether Such Facsimile System Is Operating in Private Line Mode or Public Line Mode, U.S. Pat. No. 5,699,414 to Telibasa entitled a Method and Apparatus for Sharing a Single Telephone Line Between a Facsimile Machine, Data Modem, Telephone Answering Device, and a Person, U.S. Pat. No. 5,517,556 to Pounds et al. entitled a Call Processing System with Facsimile Processing, U.S. Pat. No. 5,487,105 to Sakai entitled a Facsimile Apparatus Operable in Facsimile or Telephone Mode, U.S. Pat. No. 5,440,619 to Cann entitled a voice, Data and Facsimile Modem with Modified Ringback Answering, U.S. Pat. No. 5,428,673 to Nakagawa et al. entitled a Data Communication Apparatus Having the Function of Automatically Switching Communication and Telephone Communication, U.S. Pat. No. 5,416,834 to Bales et al. entitled a Redirection of Calls by a Communication Terminal, U.S. Pat. No. 5,337,350 to Kuwahara entitled a Facsimile Apparatus with Telephone System, U.S. Pat. No. 5,331,587 to Ohta et al entitled a Sensor Circuit for Telephone Line, U.S. Pat. No. 5,200,991 to Motoyanagi entitled an Image Communication System Including a Mobile Telephone Set and a Facsimile Device, U.S. Pat. No. 5,146,489 to Telibasa entitled a Dedicated Line Eliminator for Facsimile/telephone Systems, U.S. Pat. No. 5,113,432 to Van Santbrink et al. entitled an Arrangement for Connecting a Telefax Device or a Telephone Set to a Telecommunication Line, U.S. Pat. No. 5,056,132 to Coleman et al entitled a Switching Device Adapted to Interface Between an Incoming Telephone Line and an Internal Telephone System, U.S. Pat. No. 5,029,202 to Doembach, Jr. et al. entitled an Incoming Telephone Call Director, U.S. Pat. No. 5,027,385 to Nakagawa et al. entitled a Facsimile Apparatus for Communicating on External and Internal Telephone Sets, U.S. Pat. No. 4,916,732 to Kotani et al. entitled a Communication System Having Telephonic Function, U.S. Pat. No. 4,908,851 to Kotani et al. entitled a Facsimile Apparatus Operable in Facsimile or Conversation Mode, U.S. Pat. No. 4,813,067 to Hashimoto entitled an apparatus for connecting selectively a Telephone Answering Device or Additional Equipment, Such as a Facsimile Machine, to Telephone Lines, and U.S. Pat. No. 4,639,553 to Kiguchi entitled a Call Signal Detecting Device.